Although a special class of lipid tightly associated with membrane protein is a feature of several current models of membrane structure, there is little information regarding the nature of the lipid-protein interaction or the relationship between the protein-associated-lipid and the bulk of the lipid in the bilayer. In this study we intend to have a direct look at protein associated lipid by isolating the various components of the membrane ATPase system. We will compare the composition, patterns of metabolism, and extent of mixing of the ATPase-associated lipid with the bulk of the lipid in the membrane. The study will be divided into four phases: 1. The peripheral portion of the ATPase complex (F1) will be stripped from the membrane and the lipid component of the complex analysed at various stages of purification. 2. The complete ATPase complex (F1-Fo) and the integral membrane component (Fo) will be isolated utilizing F1-specific antibody. Membranes with different total lipid compositions will be used for these studies. 3. The rate and extent of mixing of the lipid components associated with F1-lipoprotein and F1-Fo-lipoprotein complex with the bulk lipid will be determined by double label experiments involving the reconstitution of the membrane ATPase system and subsequent reisolation of the F1 and Fo components. 4. The rates of turnover and synthesis of the lipids associated with the ATPase system will be compared to the corresponding rates for the bulk lipid of the membrane. The results of this study are expected to contribute to our understanding of the molecular organization of the membrane lipoprotein complexes, the mechanism of assembly and integration of the complexes into the membrane, and the involvement of the lipid component in the function of the protein complexes. It also might provide some insight into the complex patterns of lipid metabolism observed in Bacillus stearothermophilus and other organisms.